Internal pressure sensors having a housing with at least two pivotally connected housing parts that are placed around a hollow body and that include a tension device acting on one of the housing parts are known. Such a sensor contains at least one electrical measuring element pressed elastically onto the surface of the hollow body when the tension device or housing is placed in a closed position.
Such sensors are used above all in the testing and diagnosis of diesel engines with a conventional injection system, for example. These internal combustion engines often do not possess electrical means with which it would be possible to determine quickly and simply the engine speed, beginning of conveyance of fuel, and the injection pressure curve, all of which are important for the recognition of errors in the injection system, which often result in impermissibly bad exhaust values. Thus, a need exists for cost-effective, rugged and sufficiently precise sensors which can be attached quickly and simply to the internal combustion engine and which allow such measurements.
Sensors suited in principle to this object and having various features have become known from the following references, for example: AT-PS 375.466, AT-PS 353.507, AT-PS 373.393, AT-PS 373.394, AT-PS 374.007, AT-PS 374.280. DE 40 02 790 C2, which also makes reference to a few of the abovementioned documents, has also become known.
It is common to all of these known sensors that they are relatively expensive, due to their construction and the parts used. But above all, the application of these sensors is fraught with difficulties, since the space relations for attaching the sensor to the injection line are extremely tight, and the known tension device is relatively large, often requiring two hands for operation.
It is the object of the invention to avoid the cited disadvantages of the known sensors and to provide a sensor of the type mentioned at the outset, which can be operated simply and with one hand, is rugged, and above all, is cost-effective due to its construction, despite retaining good measuring characteristics.